Technologies for assuring originality of a printed paper medium have been proposed. For example, a technology disclosed in Japanese Patent Application Laid-Open No. 2002-344736 superimposes digital watermark information such as certification information of original data on the original data and generates printing data including the watermark and prints the data on a paper medium. Degradation such as fading of ink in printing may make original/copy determination (originality assurance) according to its watermark information impossible. To solve this problem, a technology disclosed in Japanese Patent Application Laid-Open No. 2002-344736 calculates surviving watermark by verifying the watermark, compares the surviving watermark and surviving watermark extracted from generation management information, and performs determination of the original/copy by determining degradation caused by copying the original and that caused by copying afterwards.
The above technology disclosed in Japanese Patent Application Laid-Open No. 2002-344736, however, has a problem of a complicated configuration as the technology requires not only digital watermark information but also generation management information to be generated and a surviving watermark to be calculated and compared.
Originality assurance systems for performing a tampering assessment on a printed paper medium without using digital watermark information generally determines whether a paper medium to be assessed is tampered or not (whether it is same as the original) by comparing image information on the entire surface of the paper medium to be assessed and image information on the entire surface of the original paper medium.
Such an originality assurance system without using digital watermark information needs image information on the entire surface of a paper medium to assess tampering of the image on the paper medium and calculation for the entire surface to compare the paper medium to be assessed with the original paper medium.